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Cells & Tissues

QuestionAnswer
What are cells? 1. Cells are the structural units of all living things 2. The human body has 50 to 100 trillion cells. 3. Cells are about 60% water.
What are the 4 elements that cells are most composed of? 1. Carbon 2. Hydrogen 3. Oxygen 4. Nirtogen
The Cell Theory 1. A cell is the basic structural and functional unit of living organisms. 2. The activity of an organism depends on the collective activities of its cells.
(CONT.) The Cell Theory 3. According to the principle of complementarity, the biochemical activities of cells are dictated by their structure (anatomy) which determines their function (physiology) 4. Continuity of life has a cellular basis.
What are the 3 main region/parts of a cell? 1. Nucleus 2. Cytoplasm 3. Plasma membrane
What is found in the nucleus? DNA
What is the nucleus? *1st major part* 1. Control center of the cell 2. Contains genetic material known as deoxyribonucleic acid or DNA *DNA is needed for building proteins *DNA is necessary for cell reproduction 3. Has 3 regions
What are the 3 regions found in the nucleus? 1. Nuclear envelope (membrane) 2. Nucleolus 3. Chromatin (DNA)
What is the nuclear envelope (membrane)? 1. Consists of a double membrane that bounds the nucleus 2. Contains nuclear pores that allow for exchange of material with the rest of the cell. 3. Encloses the jellylike fluid called the nucleoplasm.
Where is the nucleoplasm located? Inside the nucleus
What is the nucleolus? 1. Contains one or more dark-straining nucleoli (1 or more) 2. Sites of ribosomes assembly. 3. Ribosomes migrate into the cytoplasm through nuclear pores to serve as the site of protein synthesis.
What is chromatin? *It is very thin* 1. Composed of DNA wound around histones (proteins) 2. Scattered throughout the nucleus and present when the cell is not dividing. 3. Condenses to form dense, rodlike bodies called chromosomes when the cell divides.
About how long is DNA? 6 meters (about 18 ft.)
What is the plasma membrane? *2nd major part* 1. Tansparent barrier for cell contents 2. Contains cell contents 3. Separates cell contents from surrounding environment
What is fluid mosaic models constructed of? 1. Two layers of phospholipids arraged "tail to tail" 2. Cholesterol and proteins scattered among the phospholipids 3. Sugar groups may be attached to the phospholipids, forming glycolipids.
Define hydrophilic ("water loving") polar "heads" are oriented on the inner and outer surfaces of the membrane.
Define hydrophobic ("water fearing") nonpolar "tails" from the center (interior) of the membrane. *This interior makes the plasma membrane relatively impermeable to most water-soluble molecules.
What is the role of proteins? *Responsible for specialized membrane functions:* 1. Enzymes 2. Receptors for hormones or other chemical messengers. 3. Transport as channels or carriers
What is the role of sugars? 1. Glycoproteins are branched sugars attached to proteins that abut the extracellular space. 2. Glycocalyx is the fuzzy, sticky, sugar-rich, area on the cell's surface.
What are the 3 ways cells are bound together in the plasma membrane of cell membrane junction? 1. Glycoproteins in the glycocalyx act as an adhesive or cellular glue. 2. Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion.
(CONT.) What are the 3 ways cells are bound together in the plasma membrane of cell membrane junction? 3. Special cell membrane junctions are formed,which vary structurally depending on their roles
What are the 3 main types of cell junctions? 1. Tight junctions 2. Desmosomes 3. Gap junctions
What is a tight junction? 1. Impermeable junctions-nothing can go in between/through 2. Bind cells together into leakproof sheets. 3. Plasma membranes fuse like a zipper to prevent substances from passing through extracellular space between cells.
What is desmosomes? *Maintains a connection/stay together* 1. Anchoring junctions, like rivets, that prevent cells from being pulled apart as a result of mechanical stress. 2. Created by buttonlike thickenings of adjacent plasma membranes.
What is a gap junction? *Communicating junctions* 1. Allow communication between cells 2. Hollow cylinders of proteins (connexons) span the width of the abutting membranes 3. Molecules can travel directly from one cell to the next through these channels.
Define cytoplasm 1. The cellular material outside the nucleus and inside the plasma membrane (in between these 2 structures) 2. Site of most cellular activities 3. Includes: cytosol, inclusions, and organelles.
What are the 3 major components of the cytoplasm? 1. Cytosol 2. Inclusion 3. Organelles
Define cytosol Fluid that suspends other elements and contains nutrients and electrolytes.
Define Inclusions Chemical substances, such as stored nutrients or cell products, that float in the cytosol (inside the fluid).
Define organelles Metabolic machinery of the cell that perform functions for the cell. *Many are membrane-bond, allowing for compartmentalization of their functions.
What is mitochondria? 1. "Powerhouses" of the cell - produce ATP (chemical energy) 2. Mitochondrial wall consists of a double membrane with cristae on the inner membrane. 3. Carry out reactions in which oxygen is used to break down food into ATP molecules.
What are ribosomes? 1. Made of protein and ribosomal RNA 2. Sites of protein synthesis in the cell 3. Found at 2 locations: *Free in the cytoplasm (float around) *As part of the rough endoplasmic reticulum (rough tecture)
Define synthesis To create
What is endoplasmic reticulum (ER)? *Gives it time* 1. Fluid-filled tunnels (or canals) that carry substances within the cell. 2. Continuous with the nuclear membrane.
What are the 2 types of (ER) endoplasmic reticulum? 1. Rough ER 2. Smooth ER
What is rough endoplasmic reticulum (rough ER)? 1. Studded with ribosomes 2. Synthesizes proteins 3. Transport vesicles move proteins with cell 4. Abundant in cell that make and export proteins
What do ribosome synthesis do? create protein.
What is smooth endoplasmic reticulum (smooth ER)? 1. Lacks ribosomes 2. Functions lipid metabolism 3. Detoxification of drugs and pesticides
Define lipids Fats
What is golgi apparatus? 1. Appears as a stack of flattened membranes associated with tiny vesicles. 2. Modifies and packages proteins arriving from the rough ER via transport vesicles. 3. Produces different types of packages
What are the 3 different types of packages for golgi apparatus does? *secretory vesicles (pathway 1) *in-house proteins and lipids (pathway 2) *lysosomes (pathway 3)
Define lysosomes Break apart cell structures that are old/non-usable cell structures.
What are lysosomes? 1. Membranous "bags" that contain digestice enzymes 2. Enzymes can digest worn-out or nonusable cell structures 3. House phagocytes that dispose of bacteria and cell debris
What are peroxisomes? 1. Membranous sacs of oxidase enzymes 2. Replicated by pinching in half or budding from the ER.
What do membranous sacs of oxidase enzymes do? *Detoxify harmful substances such as alcohol and formaldehyde *Break down free radicals (highly reactive chemicals) *Free radicals are converted to hydrogen peroxide and then to water.
What are cytoskeleton? 1. Network of protein structures that extend throughout the cytoplasm 2. Provides the cell with an internal framework that determines cell shape, supports organelles, and provides the machinery for intracellular transport.
What are the 3 different types of elements form the cytoskeleton? 1. Microfilaments (smallest) 2. Intermediate filaments 3. Microtubules (largest)
What are centrioles? 1. Rod-shaped bodies made of nine triplets of microtubules. 2. Generate microtubules 3. Direct the formation of mitotic spindle during cell division.
What are the 3 cell (surface) extensions found in some cells? 1. Cilia 2. Flagella 3. Microvilli
What does cilia do in cells? Move materials across the cell surface.
Where are cilia extensions located? In the respiratory system to move mucus.
What does cilia look like? Kind of like hair
What does flagella do in cells? Propel the cell (movement)
What is the only flagella cell in the human body? Sperm
What does microvilli do in cells? Increase surface area for absorption
What do microvilli look like? Tiny, fingerlike extensions of the plasma membrane
What is cell diversity? 1. The human body houses over 200 different cell types 2. Cells vary in size, shape, and function 3. Cells vary in length from 1/12,000 of an inch to over 1 yard (nerve cells) 4. Cell shape reflects its specialized function3
What are the 2 cells that connect body parts? 1. Fibroblast 2. Erythrocyte
What do fibroblast cells look like? Secretes cable-like fibers
Define erythrocyte and what they do. They are red blood cells that carries oxygen in the bloodstream
What is the cell that covers and lines the body organs? Epithelial cell
What does epithelial cell do? 1. Packs together in sheets 2. Intermediate fibers resist tearing during rubbing or pulling
What are the cells that moves organs and body parts? 1. Skeletal muscle 2. Smooth muscle cells
Define skeletal muscle and smooth muscle cells Contractile filaments allow cells to shorten forcefully.
What is the cell that stores nutrients? Fat cells.
Define fat cells Lipid droplets stored in cytoplasm
What is the cell that fights diseases? White blood cells such as the macrophage (a phagocytic cell)
What do white blood cells (macrophage) (a phagocytic cell) do? Digests infectious microorganisms
What is the cell that gathers information and controls body functions? Nerve cell (neuron)
What do nerve cells (neuron) do? Receives and transmits messages to other body structures.
What are the 2 cells of reproduction? 1. Oocyte (female) 2. Sperm (male)
What is Oocyte (female) and what does it do? 1. Larges cell in the body 2. Divides to become an embryo upon fertilization
What is sperm (male) and what does it do? 1. Built for swimming to the egg for fertilization 2. Flagellum acts as a motile whip
What do cells have the ability to do? 1. Metabolize 2. Digest food 3. Dispose of waste 4. Reproduce - divide/multiple 5. Grow 6. Move 7. Respond to a stimulus
Define solution Homogeneous mixture of two or more components
Define homogeneous Equal distributed
Define solvent Dissolving medium present in the larger quantity; the body's main solvent is water.
Define solutes Components in smaller quantities with a solution.
What is intracellular fluid? *inside* 1. Nucleoplasm and cytosol (jellylike in the nucelus) 2. Solution containing gases, nutrients, and salts dissolved in water.
What is Extracellular fluid (interstital fluid)? *outside* 1. Fluid on the exterior of the cell 2. Contains thousands of ingredients, such as nutrients, hormones, neurotransmitters, salts, waste products.
What is the plasma membrane? It is a selectively permeable barrier (lets certain things in) *Some materials can pass through, while others care excluded. Examples: Nurtrients can center the cell Undesirable substances are kept out
What are the 2 basic methods of transport? 1. Passive processes 2. Active processes
What do passive process do? Substances are transported across the membrane without any input from the cell.
What do active process do? The cell provides the metabolic energry (ATP) to drive the transport process.
Define passive NO ENERGY
Define active HAS ENERGY
In passive processes, what is diffusion? 1. Molecule movement is from high concentration to low concentration, down a concentration gradient. 2. Particles tend to distribute themselves evenly within a solution.
(CONT.) In the passive processes, what is diffusion? 3. Kinetic energy causes the molecules to move about randomly 4. Size of the molecule and temperature affects the speed of diffusion.
Define kinetic energy energy of motion
Molecules will move by diffusion if 1. The molecules are small enough to pass through the membrane's pores. (channels formed by membrane proteins) 2. The molecules are lipid-soluble 3. The molecules are assisted by a membrane carrier
What are the 3 types of diffusion? 1. Simple diffusion 2. Osmosis 3. Facilitated diffusion
What is simple diffusion? 1. An unassisted process 2. Solutes are lipid-soluble or small enough to pass through membrane pores.
What is osmosis? A simple diffusion of water across a selectively permeable membrane. *Highly polar water molecules easily cross the plasma membrane through aquaporins. *Water moves down it concentration gradient *Higher to lower concentration
What are the 3 different kinds of solutions in osmosis? 1. Isotonic solutions 2. Hypertonic solutions 3. Hypotonic solutions
What is isotonic solutions? Have the same solute and water concentrations as cells and cause no visible changes in the cell.
What is hypertonic solutions? Contain more solutes than the cells do; the cells will begin the shrink.
What is hypotonic solutions? Contain fewer solutes (more water) than the cells do; cells will plump.
What is facilitated diffusion? *filter (kidney & urinary system)* 1. Transports lipid-insoluble and large substances 2. Glucose is transported via facilitated diffustion 3. Protein membrane channels or protein molecules that act as carriers are used.
In passive processes, what is filtration? 1. Water and solutes are forced through a membrane by fluid, or hydrostatic, pressure. 2. A pressure gradient must exist that pushes solute-containing fluid (filtrate) from a high-pressure area to a lower-pressure area.
Filtration is critical for the kidneys to work properly
What is active processes? ATP is used to move substances across a membrane
Active processes are used when Substances are too large to travel through membrane channels. The membrane may lack special protein carriers for the transport of certain substances. Substances may not be lipid-soluble Substances may have to move against a concentration gradient
What are the 2 transports in active process? 1. Active transport 2. Vasicular transport
What is active transport? 1. Amino acids, some sugars, and ions are transported by protein carriers known as solute pumps. 2. ATP energizes solute pumps. 3. In most cases, substances are moved against concentration (or electrical) gradients
Active transport example- sodium potassium pump 1. Necessary for nerve impluses 2. Sodium is transported out of the cell 3. Potassium is transported into the cell.
Define vesicular transport? Substances are moved across the membrane "in bulk" without actually crossing the plasma membrane.
In active process and in the vesicular transport, what are the 2 types of vesicular transport? 1. Exocytosis (Exit) 2. Endocytosis (Enter)
In vasicular transport and in the endocytosis, what are the 2 different type of transport? 1. Phagocytosis 2. Pinocytosis
Describe exocytosis (exist) Requires ATP (energy) Mechanism cells use to actively secrete hormones, mucus, other products. Material is carried in a membranous sac called a vasicule that migrates to & combines w/ the plasma membrane Contents of vesicle are emptied to the outside
What is the exocytosis docking process? Docking proteins on the vesicles recognize plasma membrane proteins and bind with them. Membranes corkscrew and fuse together
Describe endocytosis (enter) Extracellular substances are enclosed (engulfed) in a membranous vesicle (outside) Vesicle detaches from the plasma membrane and moves into the cell
(CONT.) Describe endocytosis (enter) Once in the cell, the vesicle typically fuses with a lysosome (destory) Contents are digested by lysosomal enzymes In some cases, the vesicle is released by exocytosis on the opposite side of the cell.
What are the 3 types of endocytosis? 1. Phagocytosis 2. Pinocytosis 3. Receptor-mediated endocytosis
Describe phagocytosis "cell eating"- takes in to destroy it. Cell engulfs large particles such as bateria or dead body cells. Pseudopods are cytoplasmic extensions that separate substances from external environment. Protective mechanism, not a means of getting nutrients
Describe pinocytosis "cell drinking" Cell "gulps" droplets of extracellular fluid containing dissolved proteins or fats. Plasma mambrane forms a pit, and edges fuse around droplet of fluid. Routine activity for most cells like those involved in absorption (small intestine)
What does receptor-mediated endocytosis do? Method for taking up specific target molecules. Receptor proteins on the membrane surface bind only certain substances. Highly selctive process of taking in substances such as enzymes, some hormones, cholesterol, and iorn.
What are the 2 major periods in a cell life cycle? 1. Interphase (metaoblic phase) (resting phase) 2. Cell division (mitosis) (growth & repair)
Define cell life cycle It is a series of changes the cell experiences from the time it is formed until it divides.
What does interphase (metabolic phase) do? Resting phase Cell grows and carries on metabolic processes Longer phase of the cell cycle
What does cell division do? (growth & repair) Cell reproduces itself.
What is DNA replication? Genetic material is duplicated and readies a cell for division into two cells. Occurs toward the end of interphase.
What is the process of DNA replication? DNA uncoils into tow nucleotide chains and each side serves as a template. Nucleotides are complementary *Adenine (A) always bonds with thymine (T) *Guanine (G) always bonds with cytosine (C)
What are the 2 events of cell division? 1. Mitosis 2. Cytokinesis
Define mitosis and what it does? *Division of the nucleus* Results in the formation of two daughter nuclei
Define cytokinesis and what it does? *Division of the cytoplasm* Begins when mitosis is near completion Results in the formation of two daughter cells
Define cyto Cytoplasm
Define kinesis Divides
what are the 4 events of mitosis? 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase
What does prophase doe in mitosis? Chromatin coils into chromosomes; identical strands called chromatids are held together by a centromere. Centrioles direct the assembly of a mitotic spindle. Nuclear envelope and nucleoli have broken down.
What does metaphase do in mitosis? *middle of the cell* Chromosomes are aligned in the center of the cell on the metaphase plate. (center of the spindle midway between the centrioles) Straight line of chromosomes is now seen.
What does anaphase do in mitosis? Centromere splits Chromatids move slowly apart and toward the opposite ends of the cell. Anaphase is over when the chromosomes stop moving.
What does telophase do in mitosis? Reverse of prophase. Chromosomes uncoil to become chromatin. Spindles break down and disappear. Nuclear envelope re-forms around chromatin. Nucleoli appear in each of the daughter nuclei.
Define cytokinesis and what it does? Division of the cytoplasm. Begins during late anaphase and completes during telophase. A cleavage furrow (contractile ring microgilaments) forms to pinch the cells into two parts.
Created by: alisia02